From time to time I make charcoal, my setup (there are multitudes of possible configurations of charcoal retorts) is a drum-in-drum pyrolyzer. This uses a 44gal (205L) drum as the outer drum and a ~20gal drum as the inner, with some 6" flue pipe to act as a chimney. https://pic8.co/d/b79ddace-7db2-40b7-b279-532a202b0cc0.jpg Basically, the process is: - Pack the inner drum with **DRY** wood. I tend to use offcuts from wood working (they are very small before I throw anything out) and sticks and small branches from trees on my property, whatever you have at hand will do, as long as it's dry (wet or green wood takes a lot more energy to get pyrolyzing, and your outer fire will probably burn out before everything gets going properly. If your wood is wet (as mine is since it rained on my pile and I didn't have a tarp over it at the time, just pack the drums and leave them somewhere to dry (where they won't get rained on) for a while. https://pic8.co/d/3dd476d5-3bb6-4eb2-bf18-fa21da9e2e85.jpg - Stick the inner drum upside down in the outer drum. There mustn't be any holes other than on the bottom (previously the top) of the inner drum, otherwise oxygen will get in, and you'll get ashes instead of charcoal. At the bottom, I have a three pointed star of heavy 2" angle iron to hold the inner drum above the bottom a little. https://pic8.co/d/a7c3c4d1-b527-408a-81d2-ff0971f5c3b9.jpg - The space around and above the inner drum is then filled with wood. This acts as the heat source to get the inner drum up to temperature. Once there, the syngas given off by the pyrolyzing wood provides the fuel for the remainder of the process. https://pic8.co/d/f029abc6-a628-476c-b8e4-27293b35fad5.jpg https://pic8.co/d/acb7f791-ff53-4da1-a73b-9142da0aeec3.jpg - A fire is lit at the top of the outer drum, then the lid and chimney put on. It will go through a few phases, first smokey, then clean burning with flames licking out of the chimney, then clean burning with no visible flames, then smokey again, and finally settling down to a pleasant simmer. - Once it's done and there isn't much flame or syngas coming from the inner container (which can be observed through the air vents in the bottom), the whole thing is tipped over and extinguished with water. https://pic8.co/d/2074d818-664c-43ac-9d40-8e9e6cd3c549.jpg If you want charcoal for cooking or blacksmithing or something like that, you can stop here (and let it dry out). For use on the garden though, I want to crush it into smaller pieces. The quickest and easiest way I've found to do this is to toss it through the mulcher. To do this, you want the charcoal damp, so it doesn't get smashed into a fine dust, but not wet or it will coalesce into a sticky paste and clog everything up. If it is a bit damp, passing through some fibrous plant matter (like old dry fern fronds) can help to brush out the buildup of stuck bits and keep the charcoal flowing through and being crushed into nice sized bits. https://pic8.co/d/8587a3e0-d5a7-489c-8e6c-e17960fd8456.jpg https://pic8.co/d/9daecaa6-9ccf-469e-a4df-5f2e480b2d39.jpg I got 3 full bags of crushed charcoal, mainly because I had a bit left over from a previous batch and also had two bags from earlier burns that I haddn't crushed. Normally, one barrel burn would produce about half a bag of crushed. https://pic8.co/d/70eeeb9e-0826-471b-a5f7-3a2faa6bef06.jpg https://pic8.co/d/04d77785-90f0-48c0-91af-951d94811403.jpg The resulting charcoal is bagged up and will store forever basically. Ideally, you would want to innoculate it by allowing it to age in a bio-active pile with various soil micro-organisms to get the best results. But, it can do that over a longer timespan in my garden soil just as well, so I just apply it straight on. Normally, I would apply it below compost or other nutrient additives. The micro-structure of the charcoal oxidizes and allows nutrients that are normally highly water soluable, like calcium, zinc, iron, manganese, etc, to be retained in the soil. Soil microbes also inhabit the tiny holes in it. It's generally good shit. Here is some that I've applied to a bed I'll be planting onions in shortly: https://pic8.co/d/ad1312ce-1a20-4287-a2c8-fd06d9bc9504.jpg